Final answer:
Recrystallization is a geologic and chemical process that typically involves changes in crystal structure without altering the chemical composition. It forms an essential part of metamorphic rock formation and is also used as a purification technique in chemistry.
Step-by-step explanation:
Recrystallization does not involve changing the chemical makeup of a rock, which means the original claim is false. During recrystallization, there may be a change in the crystal structure of the mineral, but its chemical composition remains the same. This kind of process is typical in metamorphic rocks, where conditions of pressure and temperature can lead to changes in the physical form of a mineral. For example, the transition from the mineral aragonite to calcite, both composed of calcium carbonate (CaCO3), is an example of recrystallization resulting in a polymorph, where the chemistry is identical but the structure is different. Moreover, the macroscopic characteristics like the overall size and general shape of a recrystallized fossil are preserved, though fine details may be lost during the recrystallization process.
In the context of purifying chemicals, recrystallization can be used to remove impurities from a compound. A dissolved substance can reform crystals upon cooling of a saturated solution, effectively separating the pure substance from impurities based on solubilities. Therefore, recrystallization is a vital technique in both geological and chemical processes without altering the chemical composition of the substance.